A solid powder cosmetic represented by a powdery foundation is a cosmetic that is formed by adding oil components, as the binder, to powder components, mixing, and then filling and molding in a container. The powder components thereof are mainly inorganic pigments, organic pigments, and resin powder. The pigments are further divided into colored/pearl pigments, which adjust color tone and gloss of cosmetics, and other extender pigments. The representative extender pigments are plate-like powder of talc, mica, kaolin, etc. Such components are the majority of powder components and strongly influence the moldability, adhesion, usability, etc. of cosmetics. The characteristics of powder cosmetics largely depend on characteristic extender pigments such as boron nitride, synthetic fluorphlogopite, and barium sulfate in addition to such basic extender pigments.
Among them, boron nitride has a lubricating property and confers cosmetics with a moderate hiding power and comfortable adhesion; and is thus a component that is desirably blended in a large amount.
In addition, the spherical resin particle of elastic resin, such as silicone elastomer or urethane, is also a component desired to be blended in high quantity because of its good adhesion to the skin and spreadability.
However, it is known that if boron nitride is blended in a large amount, moldability becomes poor and the impact resistance of the cosmetic decreases. If the blending quantity of the spherical elastic resin particle is increased, the moldability becomes poor because of its elasticity and the impact resistance decreases.
Accordingly, if boron nitride and spherical elastic resin particle are blended in large amounts in pursuit of usability, there is an impairment problem with the impact resistance of the solid powder cosmetic.
Concerning such problems, it is reported in Patent Literature 1 that the impact resistance can be improved by adding a dextrin fatty acid ester having a specific structure, due to the ester coating effect, to the formulation in which both boron nitride and spherical silicone elastic particle are contained in large amounts and that a cosmetic excellent in the feeling in use can be obtained. However, dextrin fatty acid esters usable in this method are limited, and it is far from the method of high versatility.
In Patent Literature 2, it is reported that a solid powder cosmetic excellent in impact resistance and usability can be obtained, by treating the surface of some of the extender pigments with a cationic surfactant, even when the extender pigment and spherical elastic resin particle are blended in large amounts. However, this treatment is poorly effective for boron nitride; in addition, it is known that dull color may be generated when an extender pigment treated with a cationic surfactant and a colored pigment such as iron oxide are blended together.
Under such circumstances, a new technology as for the preparation of a solid powder cosmetics has been sought, wherein the large amount of boron nitride and spherical elastic resin particle can be blended while providing an excellent property in usability and, in addition, an impact resistance.